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You can contribute to the Threema apps through pull requests on GitHub. Please follow the steps below:

1. Preparation

If you want to make a larger change to the Threema apps, we recommend that you contact us first via e-mail to to explain your plans. This way, we can give you early feedback about your idea, before you spend the time to actually implement the change.

Please mention the following:

  • What you would like to implement
  • How you would like to implement it

2. Sign the CLA

We require all contributors to sign our Contributor License Agreement (CLA) for non-trivial contributions. Please ensure that you have signed it before submitting a contribution.

Note that at all times you retain full ownership of your contributions. We only require a copyright license, not a copyright transfer.

3. Apply Your Changes to a Branch

Fork and clone the git repository you wish to modify.

$ git clone<your-user>/threema-<platform>.git

Create a new branch.

$ git checkout -b my-feature-or-fix

Apply your changes, test, and commit them.

4. Send a Pull Request

Once you are done, push your branch to GitHub and open a pull request.

Please understand that we cannot guarantee that we will accept your contribution. A bug may have already been fixed in our development version, a contribution may conflict with another contribution, or we may have other plans for Threema’s development. Nevertheless, you will hear back from us.